Many people who view the web have disabilities. Some people can not read the screen and have voice readers.
This is how they read a screen. No images, no colors.
You can help them know what your images are by using img ALT tags. <img src="bla.jpg" alt="Search Marketing Logo.">
Notice how I placed a period at the end of the alt tag. this helps users know when an image has ended and tells the text readers to pause.
Back to meta tags